The invention relates to a screwed connection, having a first connecting means with an external thread, which can generally also be designated as screw, and a second connecting means with an internal thread, in general usage also designated as nut. The individual parts of the screwed connection, namely the connecting means with external thread and the connecting means with internal thread, and a method of producing them are also the subject matter of the invention.
In conventional standard screws and standard nuts, the problem of locking the screwed connection to prevent unintentional slackening occurs. One possibility is to select the tightening moment to be so high that a friction grip between the external thread of the screw and the internal thread of the nut is effected. In particular with unsteady loads with high force alternations, as occur, for example, in motor vehicles on account of vibrations, this leads to a situation in which the forces which have to be absorbed by the screwed connection in order to ensure the friction grip are markedly higher than would be required by the actual retaining task.
Furthermore, in order to prevent turning of the screw in the nut, it is known to use xe2x80x9clocking meansxe2x80x9d which, for example in the case of screw enamel, provide for adhesive bonding of the screw to the nut. A disadvantage here is that the locking means having an adhesive-bonding effect is destroyed after being slackened just once, since the adhesive connection has been broken. There is also the xe2x80x9cclamping coatingxe2x80x9d according to DIN 267 Part 28. Here, there is the disadvantage that considerable effort is required during the fitting, and that, for example in the case of a galvanized surface, a chromated coating is damaged.
Finally, it is known to increase the friction by using profiled washers which have sharp edges, which, when the screwed connection is being tightened, at least partly dig into the screw material or into the material of the nut and the component arranged in between and thus produce a certain form grip in addition to the friction grip. Furthermore, it is known to provide screw heads or nuts with a corresponding profiled surface which interacts directly with the surface of the fastened component.
The subject matter of the present invention is a screwed connection which in the case of a screw is locked against slackening from the nut, the disadvantages described above being avoided.
According to the invention, the object is achieved by a screwed connection which has a first connecting means with an external thread and a second connecting means with an internal thread, the external thread having a denticulation which interacts with an internal denticulation of the internal thread.
On account of the denticulation arranged in the region of the thread, additional washers may be dispensed with and damage to the surface of the component to be connected is avoided. On account of the form grip produced by the denticulation inside the thread, that tightening moment of the screwed connection which has been required hitherto for producing an adequate friction grip can be markedly reduced, as a result of which the risk of the screwed connection fracturing is reduced and the overrating measured at the load is avoided. Furthermore, coatings or lubricants which have even penetrated into the thread can no longer lead to a substantial impairment in the functioning of the locking arrangement, since, instead of a friction grip, a form grip independent of friction is present.
Advantageous refinements of the screwed connection are described in the subclaims. In this case, it is advantageous if the denticulation is designed as a locking denticulation favoring one direction of rotation. The denticulation may be arranged on a tooth crest and/or in the groove root of the thread or on a tooth flank. For example, if the thread is not designed as a metric thread but as an Acme thread, for example in order to transmit movements over a large distance, this has the advantage that, in the case of large pitches, securing of the position by the thread itself is nonetheless possible. External locking devices may therefore be dispensed with. On account of the fine graduation of the denticulation in the thread, a virtually stepless adjustment is possible.
A further subject matter of the invention is a connecting means with an external thread, the external thread having a denticulation. This connecting means, for example as a screw, can interact with a conventional nut made of a softer, i.e. more elastic, material than that of the screw by the denticulation being impressed into the material of the soft nut. However, especially in this case, higher tightening moments are achieved than with mutual denticulation.
Furthermore, a connecting means with an internal thread is claimed, the internal thread likewise having a denticulation. In this case, too, when a soft screw is used, as in container construction for example, a denticulation in the nut may be sufficient in order to increase the security against unintentional slackening.
The connecting means described above are suitable for use in the abovementioned screwed connection. Further advantageous developments of the connecting means are described in the subclaims.
Finally, a plurality of connecting means having at most one thread turn are connected to form a stack, as a result of which, on the one hand, higher forces can be transmitted via the thread and, on the other hand, the locking function is improved.
A further subject matter of the invention is a connecting means with an internal thread which has at most one thread turn and which is part of a sheet-like material, the sheet-like material having material reinforcement in the region of the internal thread. In this way, it is possible to provide a larger part up to a complete thread turn in the sheet-like materials, the thickness of which is less than a complete pitch. Additional washers are then no longer necessary.
The subject matter of the invention is also a method of incorporating an internal thread in a sheet-like material. In this case, in a first step, the sheet-like material is pierced, the material displaced by the piercing being arranged laterally in the form of a turned-out portion. In a second step, the turned-out portion is made more uniform to form a collar, and, in a third step, a thread turn is embossed with the collar being deformed.
It is especially advantageous, in a fourth step, to stamp a denticulation in the thread turn. As a result, additional locking elements such as washers or adhesive bonding are superfluous.
Finally, a method of producing a connecting means with an internal thread is the subject matter of the invention, in which method, in a first step, openings are punched out of a sheet-like material, that, in a second step, the openings are provided with an internal thread, that, in a third step, the sheet-like material is bent over in such a way that at least two openings at least partly overlap, and that, in a fourth step, the folded sheet-like material is deformed in such a way the thread turns are arranged to form an internal thread, a denticulation being embossed in the internal thread before the third step.
Thanks to this method, it is possible, in a cost-effective manner, to produce a nut with an internal thread having a denticulation.
The sheet-like material advantageously has supporting collars at its ends, these supporting collars having been produced by bending over the sheet-metal strip, the connecting means which is adjacent to the connecting means carrying the supporting collars being supported on the supporting collar.
In order to facilitate the pressing operation, it is advantageous if the folded sheet-like material, before being compressed, has an axis which passes through the openings and is at an angle xcex1 to the subsequent center axis of the compressed sheet-like material.
In order to effect self-restraint of a screw in the connecting means, it may be of advantage if the sheet-like material is compressed only to such an extent that there is a distance between the end-side connecting means and the adjacent connecting means.